[stdlib] Add __repr__ in SIMD

[bgreni]

Implements __repr__ for SIMD

[laszlokindrat]

Thanks, this could be a good improvement! I wonder what we should do with floating point values. We looked at this recently with @ConnorGray for numpy, but I can't remember what we concluded. Since we don't have good utilities for controlling floating point printing precision globally (the way numpy does), it might be safest to print all useful digits (the number of which depends on the float type), and use scientific notation.

Either way, please add a changelog entry.

[laszlokindrat]

Could you please rebase this after tomorrow's nightly? Also, I really think the implementation should be verbose here, and print all significant digits and use scientific notation.

[bgreni]

Could you please rebase this after tomorrow's nightly? Also, I really think the implementation should be verbose here, and print all significant digits and use scientific notation.

Sorry could you maybe give an example of the output you're expecting?

[laszlokindrat]

Something like this:

assert_equal(
    SIMD[DType.float32, 1](1232.4).__repr__(),
    "SIMD[DType.float32, 1](1.2324000e+03)",  #  8 digits for float32, 16 for float64, etc
)

Looking at this now, I'm not actually sure about the trailing zeros, but in repr, I would prefer scientific notation.

[bgreni]

Ok I'll do that thanks!

[bgreni]

@laszlokindrat I've got the scientific notation working, hopefully you don't find the required changes too invasive. For now I haven't worried about trailing zeroes until you've made a concrete decision on that front.

[laszlokindrat]

Thanks for pushing this forward! The behavior with respect to trailing zeros is fine for now; we can iterate later if needed. Could you please rebase and ensure CI is happy?

[laszlokindrat]

Awesome, thanks!

[laszlokindrat]

!sync

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